Hybrid intervertebral disc spacer device and method of manufacturing the same

ABSTRACT

A hybrid spinal implant device, and method of making the same are disclosed. The spinal implant device comprises two facing endplates, each having at least one anchoring wall or pin element, and a plastic spacer anchored to and located between the two endplates. The endplates may be manufactured from titanium. The plastic spacer may be manufactured from a radiolucent, and bio-compatible polymer-based material including polyetheretherketone (“PEEK”), polyetherketone, polyetherketoneketone, and/or fiber reinforced plastic. The endplates made of titanium allow for enhanced bone growth, while the plastic/PEEK spacer element allows for improved load absorption and distribution. The spinal implant device, using titanium endplates and a PEEK spacer, provides excellent radiolucency thereby eliminating the need for X-ray markers either intra- or post-operation. The manufacturing method for the hybrid spinal implant device uses injection molding to insert or back injection mold the spacer between the two endplates.

FIELD OF INVENTION

The present disclosure relates to spinal implant devices and methodsmanufacturing the same. More particularly, preferred embodiments aredirected to a composite intervertebral disc spacer device that comprisesa hybrid combination of two endplates, each having at least oneanchoring wall or pin element, each having at least one opening therein,and a plastic spacer anchored to and in between the two endplates.Preferred embodiments are also directed to a method of manufacturing thecomposite intervertebral disc spacer device using an injection moldprocess to form the plastic spacer between the two endplates.

BACKGROUND

Many different medical procedures are performed that require thestabilization of adjacent bone sections or bone portions through thesecuring of an interbody spacer to the adjacent bone portions. Examplesof these spacers are known to those in the field as interbody cages,corpectomy cages, osteotomy wedges, joint spacers, and bone voidfillers, among other names and labels.

As one example, spacers are used to fuse bone joints. Spacers are alsoused to repair complex fractures where bone is missing and in boneregions where there are voids within the bone structure, such as when atumor and adjacent bone may be removed. Spacers are also used in theperformance of osteotomies by placing the spacers between adjacent boneportions to perform a wedging action, including to straighten a bone.These are but a few examples of, and are an not exhaustive descriptionof the medical procedures that require the placement of a spacer betweenadjacent bone portions.

In each procedure, the spacer placed between the bone portions isrequired to be rigidly joined to the adjacent bone portions. A multitudeof different apparatus have been designed for this joinder purpose. Oneexample of connecting or joining a spacer to adjacent bone structure isthrough the use of insertion screws. While screws are generallyeffective for this purpose, they are limited in the sense that they donot afford stability in all orthogonal dimensions often required toeffect the optimal or desired rigidity.

Spacers are also commonly used in spinal repair and reconstruction. Thespine is a flexible column formed of a plurality of bones calledvertebra. Each vertebrae are annular-shaped structures having a hardcortical bone on the outside and porous cancellous bone on the inside.The vertebrae are stacked, in column fashion, one upon the other,forming a strong annular column supporting the cranium and trunk. Thecore of the spine protects the nerves of the spinal cord. The differentvertebrae are connected to one another by means of articular processesand intervertebral, fibro-cartilaginous bodies.

The intervertebral fibro-cartilages are also known as intervertebraldisks and are made of a fibrous ring filled with pulpy material. Thedisks function as spinal shock absorbers and also cooperate withsynovial joints to facilitate movement and maintain flexibility of thespine. When one or more disks degenerate through accident or disease,nerves passing near the affected area may be compressed and areconsequently irritated. The result may be chronic and/or debilitatingback pain. Various methods and apparatus have been designed to relievesuch back pain, including spinal fusion using a suitable graft orinterbody spacer using techniques such as Anterior Lumbar InterbodyFusion (“ALIF”), Posterior Lumbar Interbody Fusion (“PLIF”), orTransforaminal Lumbar Interbody Fusion (“TLIF”) surgical techniques. Theimplants used in these techniques, also commonly referred to as anintervertebral spacer, are placed in the interdiscal space betweenadjacent vertebrae of the spine.

Ideally, a fusion grant should stabilize the intervertebral space andbecome fused to adjacent vertebrae. Moreover, during the time it takesfor fusion to occur, the graft should have sufficient structuralintegrity to withstand the stress of maintaining the intervertebralspace without substantially degrading or deforming. The graft shouldalso have sufficient stability to remain securely in place prior to thetime of actual bone ingrowth fusion.

One significant challenge to providing fusion grant stability (prior toactual bone ingrowth fusion) is preventing spinal extension that mayresult during patient movement. Distraction of the vertebral spacecontaining the fusion graft may cause the graft to shift or move, whichin turn may result in disrupting bone ingrowth fusion and causing pain.

Current and existing spinal fusion technology has been limited, and islacking in certain respects relating to the above described issues.Among the limitations of certain of these systems is the requirementthat complicated steps need to be performed to accomplish their properuse. As noted, others of these type of devices and systems, includedscrews, and lack the optimal multi-dimensional stability, while othersare less than desirable because they use components that may projectexternally of one or more of the bone portions between which the spaceris located. Other deficiencies and problems also exist with respect toprior devices and systems.

The systems that rely upon the use of screws may have certainlimitations. Such systems may not effectively allow compression forcesto be generated between the spacers and adjacent bone portions. Further,while the screws do stabilize the bone-spacer junction in one plane,that is normally flexion-extension, they may not, in certainapplications, control bending in another plane or direction that isorthogonal to the plane of the screw.

A further problem with existing systems is that components or partstypically are often not locked in place and are thus prone to workingloose over time. Screws, for example, may loosen over extended usage andtime in the absence of incorporating some structure that effectivelyprevents turning or lengthwise movement. Without such locking elements,a loosened screw could result in partial or full separation of thedevice from the bone portions and/or spacers that they penetrate.

Several disc spacer devices have been designed and proposed to addresssome of these noted limitations. Examples include U.S. Pat. No.6,569,201 for a Hybrid Composite Interbody Fusion Device, issued toMoumene et al.; U.S. Pat. No. 7,776,093 for a Vertebral Body ReplacementApparatus And Method, issued to Wolek et al.; and U.S. patentapplication Ser. No. 11/643,994 for an Interbody Fusion Hybrid Graft. Inaddition to these devices, the medical field is constantly seekingsystem designs that might be efficiently and consistently installed andthat, most significantly, will affect the desired fusion in a mannerthat will be safe and reliable for the patient. The various embodimentsof devices and methods described in this application address such aneed.

SUMMARY

The above noted problems, which are inadequately or incompletelyresolved by the prior art are completely addressed and resolved by thepresently described embodiments of devices and methods.

A preferred embodiment of the device is a hybrid spinal implant forpositioning at an intervertebral space and comprising a first end plate,configured for fitting within a disc space, wherein the first end platecomprises a first surface for engaging a first vertebral surface and asecond surface opposite the first surface, wherein the second surfacecomprises at least one anchoring protrusion; a second end plateconfigured for fitting within a disc space, wherein the second end platecomprises a first surface for engaging a second vertebral surface and asecond surface opposite the first surface, wherein the second surfacecomprises at least one anchoring protrusion; a unitary plastic spacerformed through injection molding and positioned between the first andsecond end plates and anchored to the first and second end platesrespectively by each of the at least one anchoring protrusions.

Another preferred embodiment of the device is a hybrid spinal implantfor positioning at an intervertebral space, comprising a first endplate, configured for fitting within a disc space, wherein the first endplate comprises a first surface for engaging a first vertebral surfaceand a second surface opposite the first surface, wherein the secondsurface integrally comprises a plurality of wall and pin protrusions; asecond end plate configured for fitting within a disc space, wherein thesecond end plate comprises a first surface for engaging a secondvertebral surface and a second surface opposite the first surface,wherein the second surface integrally comprises a plurality of wall andpin protrusions; a unitary ring-shaped plastic spacer formed throughinjection molding and positioned between the first and second end platesand anchored to the first and second end plates respectively by each ofthe plurality of wall and pin protrusions.

A further preferred embodiment of the hybrid bone implant forpositioning within a bone structure cavity, comprises a first end plate,configured for fitting within a bone structure cavity, wherein the firstend plate comprises a first surface for engaging a first bone surfaceand a second surface opposite the first surface, wherein the secondsurface comprises at least one anchoring protrusion; a second end plateconfigured for fitting within a bone structure cavity, wherein thesecond end plate comprises a first surface for engaging a second bonesurface and a second surface opposite the first surface, wherein thesecond surface comprises at least one anchoring protrusion; a unitaryring-shaped plastic spacer formed through injection molding andpositioned between the first and second end plates and anchored to thefirst and second end plates respectively by each of the at least oneanchoring protrusions.

A preferred embodiment for a method for manufacturing a hybrid spinalimplant, where the hybrid spinal implant is for placement in anintervertebral space, is a method comprising the steps of (a)positioning within an injection mold tool a first end plate, said firstend plate configured for fitting within a disc space, wherein said firstend plate comprises a first surface for engaging a first vertebralsurface and a second surface opposite the first surface, wherein thesecond surface comprises at least one anchoring protrusion; (b)positioning within said injection mold tool a second end plate oppositeand spaced away from said first end plate, wherein said second end platecomprises a first surface for engaging a second vertebral surface and asecond surface opposite the first surface, wherein the second surfacecomprises at least one anchoring protrusion; (c) forming a unitaryplastic spacer between the first and second end plates by injectionmolding wherein the plastic spacer is anchored to the first and secondend plates respectively by each of the at least one anchoringprotrusions.

The various embodiments will be best understood by reading the followingdetailed description of the several disclosed embodiments in conjunctionwith the attached drawings that briefly described below.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of embodiments ofthe devices, and the manner of attaining them, will become more apparentand will be better understood by reference to the following descriptionof embodiments taken in conjunction with the accompanying drawings,wherein corresponding reference characters indicate corresponding partsthroughout the several views and wherein:

FIG. 1 shows an isometric view of an embodiment of the hybridintervertebral disc spacer;

FIG. 2 shows a side view of an embodiment of the hybrid intervertebraldisc spacer;

FIG. 3 shows an isometric cut-away view of an embodiment of the hybridintervertebral disc spacer;

FIG. 4 shows an exploded isometric view of an embodiment of the hybridintervertebral disc spacer;

FIG. 5 shows an exploded side view of an embodiment of the hybridintervertebral disc spacer;

FIG. 6 shows an exploded cut-away side view of an embodiment of thehybrid intervertebral disc spacer; and

FIG. 7 shows an exemplary embodiment of process steps for the injectionmold manufacturing of the hybrid intervertebral disc spacer.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In the following detailed description, reference is made to theaccompanying drawings wherein like numerals designate like partsthroughout, and in which is shown, by way of illustration, the disclosedembodiments may be practiced. It is to be understood that otherembodiments may be utilized and structural or logical changes may bemade in alternate aspects. Therefore, the following detailed descriptionis not to be taken in a limiting sense, and the scope of the disclosedembodiments is defined by the appended claims and all of theirequivalents.

Moreover this detailed description is intended to be read in connectionwith the accompanying drawings, which are to be considered part of theentire written description of the preferred embodiments. The drawingfigures are not necessarily to scale and certain features of theembodiments and examples may be shown exaggerated in scale or insomewhat schematic form in the interest of clarity and conciseness. Inthe description, relative terms such as “horizontal,” “vertical,” “up,”“down,” “top,” “bottom,” “outer,” “inner,” “front,” “back,” “anterior,”and “posterior,” as well as derivatives thereof (e.g., “horizontally,”“downwardly,” “upwardly,” etc.) should be construed to refer to theorientation as then described or as shown in the drawing figure underdiscussion. These relative terms are for convenience of description andnormally are not intended to require a particular orientation.

Further, terms including “inwardly” versus “outwardly,” “upwardly”versus “downwardly,” “longitudinal” versus “lateral” and the like are tobe interpreted relative to one another or relative to an axis ofelongation, or an axis or center of rotation, as appropriate. Termsconcerning attachments, coupling and the like, such as “connected”“interconnected,” “coupled,” “engaged” and “attached” refer to arelationship wherein structures are secured or attached to one anothereither directly or indirectly through intervening structures, as well asboth movable or rigid attachments or relationships, unless expresslydescribed otherwise.

In certain embodiments, the intervertebral spacer implant device may beemployed to maintain appropriate spacing between adjacent vertebrae, forexample, where wear or injury has led to the need for disc replacement.In other embodiments, the intervertebral spacer implant device may beconfigured for both disc and vertebrae replacement. Regardless,embodiments of the described devices provide a spinal fusion device thatprovides column support to the spine and facilitates a fusion betweenadjacent vertebral bodies.

In certain embodiments, as shown in the attached drawings, the fusionspacer device includes three elements, namely, a pair of endplatesdesigned and configured to be attached to respectively upper and lowervertebrae surfaces, and a vertebral plastic disc spacer in between thetwo endplates. More particularly, as shown in FIG. 1, in a preferredembodiment, the disc spacer 10 includes an upper endplate 20 and a lowerendplate 30 that sandwiches a plastic spacer element 40. The assembly orconstruction of the disc spacer provides, in a preferred embodiment,that the plastic spacer element is back injection molded after theendplates 20 and 30 are placed within an injection molding tool. Throughuse of back injection molding, the plastic spacer element 40 is formedto precisely the desired shape, and ensures complete contact between thesurfaces of the spacer element with the respective upper endplate 20 andlower endplate 30. In a preferred embodiment, as shown and described inmore detail below, plastic spacer element is formed generally in acylindrical shape.

The isometric view shown in FIG. 1 illustrates the plastic spacerelement 40 as translucent to further show the location of anchoringelements to lock the relative position of the upper endplate 20 andlower endplate 30 with the spacer element 40. The anchoring elementsshown in FIG. 2, in a preferred embodiment, are wall protrusions 21,integral with upper endplate 20, and wall protrusions 31, integral withlower endplate 30.

FIG. 2 shows a side-view of a preferred embodiment of the disc spacer10, again with the plastic spacer element 40 shown as translucent toillustrate example anchoring elements. In addition to the wallprotrusions 21 and 31, which are integrally attached to the upperendplate 20 and lower endplate 30, respectively, FIG. 2 shows use of pinprotrusions 22 and 32, which are similarly attached to the upperendplate 20 and lower endplate 32. The pin protrusions shown in FIG. 2are a T-shape, and are completely surrounded by the spacer element 40.In view of the imbedded placement of the T-shaped pin protrusions 22, 32within the back injection formed spacer element 40, such protrusionsprovide both lateral stability and further reduce the possibleseparation or delamination of either endplate 20, 30 from the spacerelement 40.

FIG. 3 shows a cut-away side/isometric view of the disc spacer 10,similar in orientation to the side view in FIG. 2. In addition to thewall protrusions 21, 31, and pin protrusions 22, 32 shown FIG. 2, thecut-away view of FIG. 3 shows a further wall protrusion which may beintegrally formed with upper endplate 20 and lower endplate 30. Morespecifically, wall protrusions 23 and 33, integrally attached to upperendplate 20 and lower endplate 30, respectively, each have distal shelf28 (at the end of wall protrusion 23) and 38 (at the end of wallprotrusion 33). The distal shelf 28, 38 on wall protrusions 23, 33,similar to the pin protrusions 22, 32, provide both lateral stabilityand reduce the separation of either endplate 20, 30 from the spacerelement 40. This is especially true given the preferred assembly methodof back injection molding the spacer element between the endplates 20,30. By back injection molding the spacer element 40, the plasticmaterial is fully formed and in full contact with all surfaces of thewall and pin protrusions.

The cut-outs 24, 25, 34, 35 shown in wall protrusions 21 and 31 serve asimilar purpose as the pin protrusions 22, 32, and wall protrusion 23,33 (having distal shelves 28, 38). That is, in view of the backinjection molding of the plastic spacer 40, the plastic material isfully formed in and through cut-outs 24, 25, 34, and 35. Although squareor rectangular, and circular shapes are shown for the cut-outs 24, 25,34, and 35, other shapes may be used in other embodiments and will beequally effective in providing lateral stability and reducing separationor delamination.

The endplates 20 and 30 are, in a preferred embodiment, manufacturedfrom a porous biocompatible metal such as titanium or titanium alloy.Such metals exhibit significant bone apposition or fusioncharacteristics. Moreover, the porosity of the endplates 20 and 30, maybe further tailored to promote ingrowth and fusion. Indeed, in anotherpreferred embodiment, conventionally available ingrowth promotingmaterial may be accommodated at the surfaces of the endplates 20, 30that contact adjacent vertebra and also throughout holes or pores 27, 37included in the endplates 20, 30 to help stimulate bone ingrowth andendplate fusion.

The plastic spacer 40 is made, in a preferred embodiment, from aradiolucent polymer-based material such as polyetheretherketone(“PEEK”), polyetherketone (“PEK”), polyetherketoneketone (“PEKK”), orfiber reinforced plastic, each of which have a e-modulus that is moresimilar to bone than metal. Moreover, given the e-modulus of PEEK, PEK,and PEKK, such plastics show optimal load absorption and loaddistribution when used as vertebral spacers. Indeed, PEEK, PEK and PEKKare materials that are often used in the manufacture of intervertebralspinal implants. Further, PEEK and other similar materials are almostentirely radiolucent and highly biocompatible. Being radiolucent, theuse of PEEK as a material for the spacer 40, allows for precisepositioning through use of X-ray equipment during and after insertionoperation. Moreover, with the use of the metal endplates 20, 30, theexact position of the disc spacer 10 in relation to adjacent vertebraeusing flouroscopy during the operation is easily achieved, without theuse of X-ray markers.

As shown in FIGS. 1 through 6, the surfaces of the endplates 20, 30 maybe formed with a highly uneven surface texture. The teeth or edges 29,39 shown on endplates 20, 30 form a porous and substantially roughenedsurface texture of the endplate surfaces in contact with adjacent bonestructure. The teeth 29, 39 provide excellent stability againstmigration or lateral movement or migration after placement of the discspacer 10, as well as stability from flexion/extension loads, axialtorsion loads, and lateral bending loads. The teeth 29, 39 also, giventhe biocompatible nature of the titanium metal, promote fusion of thebone with the endplates 20, 30 of spacer 10.

In other embodiments, the endplates 20, 30, or the surfaces of theendplates 20, 30 may be made of alternate materials such as a nitride,carbide, or oxide of a porous metal. Additionally, a porouscobalt/chromium alloys or stainless steel may be used as the metal. Inanother embodiment, appropriate sections of the endplates 20, 20 may beconstructed of a porous radiolucent material with a comparatively thinlayer of metal, such as titanium, deposited over that endplate section.Such a layer of metal may itself be crystalline or amorphous instructure.

FIG. 4 shows an isometric exploded view of a preferred embodiment of thepresent disc spacer 10. In this view, the cylindrical shape of theplastic spacer 40 is easier to see, in place between upper endplate 20and lower endplate 30. Similarly, FIG. 5 shows a side view of the threeelements, namely endplates 20 and 30, and plastic spacer 40, in anexploded view. Finally, FIG. 6 shows a similar cut-away side view of thesame three elements of disc spacer 10.

As noted, one illustrative embodiment of the method of manufacturing thedisc spacer 10 is through the use of injection, or injection backmolding. FIG. 7 illustrates the basic steps of the method of preciselylocating endplates 20 and 30 within an injection mold tool that providesthe appropriate shape, size and form for the plastic spacer, and theninjection molding the plastic material in between the two endplates,filling the form space between the two endplates 20, 30. The stepsinclude first positioning the first endplate 100 within the injectionmold tool; then positioning the second endplate 200 within the injectionmold tool, creating between the two endplates the desired shape, sizeand form for the plastic spacer 40. Next the unitary plastic spacer 40is formed between the two endplates by back injection molding 300 withthe selected plastic material. Finally, the hybrid disc spacer 10 isremoved 400 from the injection mold tool.

It should be readily apparent to those skilled in the art that thespacer 10 can be used between any adjacent bone portions, such asmembers at a joint, for example, in a void between such joint portionsas might be developed by a fracture, through a procedure that removesbone as with a tumor. While the various embodiments and examples arecontemplated for use with virtually any adjacent bone portions betweenwhich a spacer is required, the initial disclosure herein is directedtowards spinal procedures wherein the spacer 10 is placed betweenadjacent vertebrae/joint members that make up the more genericallyreferenced bone portions. As noted, the disclosed examples andembodiments are not however to be considered limiting as to effectiveuses of the spacer.

It is also understood that while the present disclosure has been to atleast one embodiment for an invertebral disc spacer, the scope andcoverage of preferred embodiments can be further modified and still bewithin the spirit and scope of this disclosure. This application istherefore intended to cover any variations, uses, or adaptations of thepresent disclosed embodiments using its general principles.

Further, this application is intended to cover such departures from thepresent disclosure as come within known or customary practice in the artto which this disclosure pertains and which fall within the limits ofthe appended claims. Further modifications and alternative embodimentsof various aspects of the devices and methods will be apparent to thoseskilled in the art in view of this description.

Accordingly, this description is to be construed as illustrative onlyand is for the purpose of teaching those skilled in the art of thegeneral manner of carrying out the present disclosure. Elements andmaterials may be substituted for those illustrated and described herein,parts and processes may be reversed, and certain features of thepreferred embodiments may be utilized independently, all as would beapparent to one skilled in the art of having the benefit of thisdescription. Changes may be made to the elements described herein,including shape of the spacer, without departing from the spirit andscope of the present disclosure as described in the following claims.

What is claimed is:
 1. A hybrid spinal implant for positioning at anintervertebral space, comprising: a first end plate, configured forfitting within a disc space, wherein the first end plate comprises afirst surface for engaging a first vertebral surface and a secondsurface opposite the first surface, wherein the second surface comprisesat least one anchoring protrusion, and at least one opening in saidfirst end plate; a second end plate configured for fitting within a discspace, wherein the second end plate comprises a first surface forengaging a second vertebral surface and a second surface opposite thefirst surface, wherein the second surface comprises at least oneanchoring protrusion, and at least one opening in said second end plate;a unitary plastic spacer formed through injection molding and positionedbetween the first and second end plates and anchored to the first andsecond end plates respectively by each of the at least one anchoringprotrusions, and by said at least one openings in said first and secondend plates.
 2. The hybrid spinal implant device of claim 1, wherein theunitary plastic spacer is formed between the first and second end platesby back injection molding.
 3. The hybrid spinal implant device of claim1, wherein the first end plate and second end plate are manufacturedfrom titanium.
 4. The hybrid spinal implant device of claim 1, whereinthe first end plate and second end plate are manufactured from atitanium alloy.
 5. The hybrid spinal implant device of claim 1, whereinthe first end plate and second end plate are manufactured with a surfacemade from titanium.
 6. The hybrid spinal implant device of claim 1,wherein the unitary plastic spacer is manufactured from the group ofmaterials consisting of PEEK, PEK, PEKK, and fiber reinforced plastic.7. The hybrid spinal implant device of claim 1, wherein the plasticspacer is a unitary solid element.
 8. The hybrid spinal implant deviceof claim 1, wherein the plastic spacer is a unitary ring-shapedcylinder.
 9. The hybrid spinal implant device of claim 1, wherein the atleast one anchoring protrusions are wall-shaped protrusions.
 10. Thehybrid spinal implant device of claim 1, wherein the at least oneanchoring protrusions are pin-shaped protrusions.
 11. A hybrid spinalimplant for positioning at an intervertebral space, comprising: a firstend plate, configured for fitting within a disc space, wherein the firstend plate comprises a first surface for engaging a first vertebralsurface and a second surface opposite the first surface, wherein thesecond surface integrally comprises a plurality of wall and pinprotrusions, and at least one opening in said first end plate; a secondend plate configured for fitting within a disc space, wherein the secondend plate comprises a first surface for engaging a second vertebralsurface and a second surface opposite the first surface, wherein thesecond surface integrally comprises a plurality of wall and pinprotrusions, and at least one opening in said second end plate; aunitary ring-shaped plastic spacer formed through injection molding andpositioned between the first and second end plates and anchored to thefirst and second end plates respectively by each of the plurality ofwall and pin protrusions and said at least one openings in said firstand second end plates.
 12. The hybrid spinal implant device of claim 11,wherein the first end plate and second end plate are manufactured fromtitanium.
 13. The hybrid spinal implant device of claim 11, wherein thefirst end plate and second end plate are manufactured from a titaniumalloy.
 14. The hybrid spinal implant device of claim 11, wherein thefirst end plate and second end plate are manufactured with a surfacemade from titanium.
 15. The hybrid spinal implant device of claim 11,wherein the unitary plastic spacer is manufactured from the group ofmaterials consisting of PEEK, PEK, PEKK, and fiber reinforced plastic.16. A hybrid bone implant for positioning within a bone structurecavity, comprising: a first end plate, configured for fitting within abone structure cavity, wherein the first end plate comprises a firstsurface for engaging a first bone surface and a second surface oppositethe first surface, wherein the second surface comprises at least oneanchoring protrusion, and at least one opening in said first end plate;a second end plate configured for fitting within a bone structurecavity, wherein the second end plate comprises a first surface forengaging a second bone surface and a second surface opposite the firstsurface, wherein the second surface comprises at least one anchoringprotrusion, and at least one opening in said second end plate; a unitaryring-shaped plastic spacer formed through injection molding andpositioned between the first and second end plates and anchored to thefirst and second end plates respectively by each of the at least oneanchoring protrusions and the at least one openings in said first andsecond end plates.
 17. A method for manufacturing a hybrid spinalimplant, where the hybrid spinal implant is for placement in anintervertebral space, the method comprising the steps of: (a)positioning within an injection mold tool a first end plate, said firstend plate configured for fitting within a disc space, wherein said firstend plate comprises a first surface for engaging a first vertebralsurface and a second surface opposite the first surface, wherein thesecond surface comprises at least one anchoring protrusion, and at leastone opening in said first end plate; (b) positioning within saidinjection mold tool a second end plate opposite and spaced away fromsaid first end plate, wherein said second end plate comprises a firstsurface for engaging a second vertebral surface and a second surfaceopposite the first surface, wherein the second surface comprises atleast one anchoring protrusion, and at least one opening in said secondend plate; (c) forming a unitary plastic spacer between the first andsecond end plates by injection molding wherein the plastic spacer isanchored to the first and second end plates respectively by each of theat least one anchoring protrusions, and by said at least one openings insaid first and second end plates.
 18. The method for manufacturing ahybrid spinal implant, according to claim 17, wherein the first endplate and second end plate are manufactured from titanium.
 19. Themethod for manufacturing a hybrid spinal implant, according to claim 17,wherein the first end plate and second end plate are manufactured with asurface made from titanium.
 20. The method for manufacturing a hybridspinal implant, according to claim 17, wherein the unitary plasticspacer is manufactured from the group of materials consisting of PEEK,PEK, PEKK, and fiber reinforced plastic.